1. Field of the Invention
The present invention relates to a sensor module including a sensor element, an amplifier and an analog to digital (A/D) converter.
2. Description of the Related Art
Various sensors including an acceleration sensor, an angular velocity sensor, etc., a differential amplifier for amplifying sense signals outputted from those sensors, and an A/D converter for A/D-converting the amplified sense signals are packaged into one sensor module, which is well known to those skilled in the art. This sensor module can be readily incorporated into another device, and contribute to reducing the number of components of the device and miniaturizing the device.
As a technique for increasing precision of an output signal in an apparatus using a sensor, in Japanese Patent Laid-open Publication No. H9-43264 is disclosed an acceleration detection apparatus which has an acceleration sensor for obtaining an output signal corresponding to an acceleration in a traveling direction of an automobile. This acceleration detection apparatus comprises means for retaining, as a correction signal, the output signal from the acceleration sensor when the number of engine rotations of the automobile is constant, namely, the acceleration in the traveling direction of the automobile is 0, and thereafter removing the correction signal from the output signal from the acceleration sensor. The correction signal includes unnecessary components not related to the acceleration in the traveling direction of the automobile, such as a drift component occurring in the output signal from the acceleration sensor due to a temperature variation or other environmental variations, or a gravitational acceleration component applied to the acceleration sensor when the automobile travels on an uphill road. These unnecessary components are removed by the removing means. Therefore, this acceleration detection apparatus can reduce an error which will occur due to such unnecessary components.